Safety relay control



Jan. 1 1963 l. E. MATHER 3,071,692

. Filed Aug. 9, 1960 SAFETYRELAY CONTROL 2 Sheets-Sheet 1 Nllll INVENTOR IRwm E. MATHeR ATTQRNel/ Jan. 1., 1963 l. E. MATHER 3,071,692

SAFETY RELAY CONTROL Filed Aug. 9, 19.60 l 2 Sheets-Sheet 2 'iis-NE INVENTOR IRWIN E. MATHER ATTORNEY United S ares' Patent i Ofhce 3,071,692 Patented Jan. l, V1963A ginla Filed Aug. 9, 1960, Ser. No. 4S,517 11 Claims. (Cl. 307-10) This invention relates to an automatic safety relay control associated with a machine ha-ving indicator means responsive to a danger operating condition of the machine. More particularly, this improved control is operable after Abeing set to accommodate starting the machine. After the machine is started, the control is then automatically positioned for safety operation to safely stop the machine upon a danger signal from the indicator means. Many machines in use today require minimum operating conditions below which the machine should not be operated to prevent permanent damage. Detectors have been deviced for most troublesome operating conditions. Such detectors include gauges for the oil pressure of bearings and the water pressure and temperature of cooling systems. A typical example would be the oil pressure and Water temperature gauges for an internal combustion auto` mobile engine. An operator can observe the gauges and act accordingly to remedy any defects.

However, if a machine were used unattended for long periods of time, an operator probably would not be present to correct the defects. Accordingly, it is advisable to stop an unattended machine automatically when the oil pressure, water pressure ortemperature, or any other operating condition becomes critical to prevent damage to the machine.

An automatic safety relay ycommonly used includes an indicator gauge which has contacts actuated by an indicator needle resting against a stop. The contacts close when the machine is operating in the danger operating condition. The stop is in a safety circuit with latch-held, solenoid-released machine control contacts and a power source. When the indicator needle contacts the stop, the safety circuit is completed to energize the solenoid and move the machine control contacts to the machine nonoperate position. s

In some indicator gauges, such as those for oil' and water pressures, the indicator needle contacts the stop both when the machine is in the danger operating condition and when the machine is not operating. Consequently, the safety circuit is completed and the machine control contacts are held in the machine non-operate position.

A starter button is used to bipass the safety circuit having indicator gauges with normally closed contacts to permit initial operation of the machine. The button is manually operated to break the safety circuit and allow the machine control contacts to return to the machine operate position. The machine can then be started. However, the starter button must be held until the machine has developed sufficient oil or water pressure to open the indicator gauge contacts. This is accomplished by either wedging the starter button with some tool or by maintaining manual pressure against the starter button.

The defects are obvious for both methods. If an operator wedges the starter button but forgets to release the tool after the machine has started, the safety circuit is completely useless. Additionally, if he manually holds the starter button, he has only one free hand to start the machine. He cannot properly manipulate the starter mechanism, choke or throttle of the machine with only one free hand. Thus he is greatly hampered.

Accordingly, it is an object of this invention to provide a safety relay control for a machine to stop the operation of the machine automatically upon a predetermined danger operating condition. l k

Another object of this invention is to provide a safety relay control for a machine which functions automatical- 1y after it is once set to stop the machine when the danger operating condition occurs.

Another object of my invention is to provide a safety relay control for a machine which when once set will accommodate starting the machine, and upon the machine starting will be already set and functionable for automatic safety operation thereafter.

In order that all of the structural features for attaining the objects of this invention may be understood, reference is herein made to the drawings wherein:

`FIG. 1 is a front elevational view of the control of this invention;

FIG. 2 is a rear elevational view of the control of FIG. 1; s

FIG. 3 isa view, partially in cross-section as seen from line 3--3 of FIG. 1;

FIG. 4 is a view, partially in cross-section, as seen from line 4-4 of FIG. 3; and

FIG. 5 is a schematic circuit diagram incorporating the Yabove control for safely operating the various internal combustion engines.

It willv be apparent that this safety relay control could be operable for all types of machines having any measurable danger operating conditions. For .simplicity sake, however, the disclosure of this control will be discussed in combination with various common internal combustion engines. The most common internal combustion engines are the battery-powered ignition-system gasoline engine, magneto-powered ignition-system gasoline engine, and the diesel engine. As is well known in thea-rt, a battery igniltion engine is easily controlled from the operate and nonoperate conditions by completing or breaking a circuit from a power source to an ignition coil. The ignition coil in turn creates electrical impulses sufficient to cross a spark gap located within the combustion chamber.

A magneto ignition engine has a magneto which creates an electrical impulse for a spark gap located in the combustion chamber. A dual magneto ignition engine has separate magnetos which create separate electrical impulses for separate spark gaps located in the same combustion chamber and is used as a safety measure to ensure continued operation even after failure of one of the magnetos. Either engine is easily controlled from the operate and non-operate conditions by, shorting out the electrical impulse to prevent the impulse from crossing the spark gap.

A diesel engine is generally controlled from the operate and non-operate conditions by regulating the flow of fuel from the fuel source to the engine. A spring-biased solenoid-operated valve located in the fuel line operates to open and close the line to permit fuel flow to the engine.

FIGURE 5 is a schematic circuit diagram of this safety relay control in typical combinations with common internal combustion engines and indicator gauges operable to safety control the engines. The safety relay cont-rol is `schematically shown within the dotted outline in the center of the FIGURE. The control as shown is in the engine control non-operate condition. The control generally consists of engine control contacts 10, safety-hold contacts 12, bimetal latch mechanism 14 and control setting mechanism 16. The two types of indicator gauges are schematically shown at 18 and 19. Indicator gauge 1S is the type where the danger zone is on the low side, such as to measure oil or Water pressure. Indicator gauge 19 is of the type Where the danger zone is on the high side such as to measure water temperature. Indicator gauge 18 is in the closed contact position when the engine is not operating as well as when the engine is in the danger operating condition. Indicator gauge 19 is in the closed contact Acontrol contcts 10. The control contacts are connected to power source or battery `8. Indicator gauges 18 and 19 are connected in Ycircuits through the safety hold contacts 12 and the bimetal latch mechanism 14 to the engine control contacts 10.- Engine control contacts 10 thus operate in combination with indicator gauges 18 and 19, safety hold contacts 12, and the bimetal latch mechanism 14 to control the operate and non-operate conditions of the engines.

Referring now to FIG. 3, an open end shell or case rgenerally designated 20 comprises substantially cylindrical side walls 22 having outwardly extending iianges 23 and a backplate 24. A front plate 26 having a dial face 27 is held in place within the open end of the case between a bezel 28 and an annular L-shaped retainer 29, the retainer and bezel being crimped together (not shown) as is well known in the art. Gaskets 30 are interposed between the bezel and dial face, and front plate and retainer, to ensure a substantially watertight case. The bezel is press-fitted into the case against side wail 22.

Referring now to FIG. `4, engine control contacts `r1.0 include a bracket 32 secured to the front plate 26. A plurality of leaves or strips of electrically conductive resil- .ientrnateriaL lsuch as Yphosphor bronze, are connected to bracket 32 by `nut and bolt assembly 34. YAssembly 34 preferably is of nylon or some other nonconductive material. insulating spacers 3S are disposed between the leaves to keep the adjacent leaves from shorting out.

Battery leaf 36 having contact 38, and ignition leaf 40 having contact 42 engageable with contact 3S, are secured to the bracket. Signal leaf44 is located between leaves 36 and 40 and has a contact engageable with -a contact 48 on leaf 36. Spring element 49 is connected to the bracket adjacent the ignition leaf and has a raised end portion 50, the purpose of which will be described later.

Y A first magneto leaf 51 having contact 52, a second magneto leaf 54 having contact 56, and a ground leaf 58 having contact 60 are secured to the bracket adjacent spring element 49. As shown in FIGS. 4 and 5, contacts 38 and 42 are normally open, while contacts 46 and 48, and contacts 52, 56 and 60 arenormally closed.

Safety-hold contacts 12 include a plurality of conductive resilient leaves or strips which are supported by nut andV bolt assembly 67 on a bracket 66 secured to front plate 26l An electromagnet or solenoid 68 has a coil 69 around a -magnetizable core 70. The core is connected at its ends to a pair of spaced magnetizable pole plates 71. The electromagnet is secured to front plate 26 by conventional means not shown. The pole plates 71 extend substantially perpendicular to the axis of the core and are tapered therefrom to form a pair of feet 72. The feet are 'aligned with each other outside the radial line of coil 69.

A thin substantially circular keeper 73, larger in diameter than the distance between the end plates 71 and having a notched circumferential edge '74 (FIG. 3), is abuttable with the feet 72.

A live leaf 76 is connected at one end to bracket 66 and at the other end to the keeper 73. An insulator 77 is inserted between the live leaf 76 and the keeper. A rivet 7S loosely secures the keeper and Vinsulator to the live leaf so that the keeper may both rotate and oscillate slightly relative to the leaf. The leaf resiliently supports the keeper away from the electromagnet 68. The keeper can, however, be moved against the resiliency of the leaf toward the electromagnet to abut feet 72.

A contact -80 is secured to live leaf 76. A lower leaf 184 having contact 86, and an upper leaf 88 having contact 90 are connected to bracket 66 on opposite sides of live leaf 76. Contacts 86 and 90 are selectively engageable with contact 80. Contacts 80 and 86 are normally closed whereas contacts 80 and 90 are normally open.

lt was found that the holding power of the keeper against the feet was greatly increased by so notching the circumferential edge 74- of the keeper as compared with a keeper having a smooth circumferential edge. Furthermore, the keeper is loosely supported by rivet 78 to leaf 76 since the contacts 80 and 86, and 80 and 90 must not be drawn out of line by the keeper seeking a seat against the feet.

The bimetal latch mechanism 14 consists of a bimetal strip or element 98 secured tothe bracket 66. A crimp 190 is formed on the strip at the end remote from the bracket. Bimetal strip 98 is adjusted so that the crimp end of the strip is resiliently urged toward end portion 50 of spring element 49 at `normal ambient temperature.` Thus if the spring element were deflected counterclockwise (FIG. 4) againstrleaf 40 to close contacts 38 and i 42, the crimp would slide over the raisedend portion `S0V of the spring element and maintain the contacts engaged.

A heater coil102 is wound around bimetal Vstrip 98.`

The coil when energized, heats the bimetal strip and de.-

iiects it away from spring element '49.V The crimpthen slides off the end portion of the spring element and permits leaf `40 to return to the with contacts 38 and 42 open.

The control setting mechanism 16 comprises a shaft 186 (FIG. 3) supported by front plate 26 with its ends extending to both the inside and outside of shell 20." A control knob 107 is located to the shaft 106 on the outside of the shell by a set screw 108. The knob has anannular recess 110 adjacent the shell whichris filled by a sticky viscuous semi-fluid 1,09 such as silicon rubber. The semi-V iiuid 109 adheres to the sides of therecess in the knob 'fr and to dial face 27, thus forming a watertight sealar'ound f shaft 106 between the outside and the inside ofthe shell.y The knob can be turned because of the` iscuous action of the vane 114 to its neutral position substantially as shown in FIGURE 4. Stops -124 (FIG. 1) extending outwardly from dial face 27 are engaged by knob 107 and limit the rotation of the knob and vane to prevent sealing iuid 109 and/or springs 116 and 11S.

The indicator gauges 18 and 19 have indicator pointer 128 and` 129, respectively, which contact stops 130 and damage to 131 respectively, when the engine is in a danger operating p condition. Indicator pointer 128 also contacts stop 130 when the engine is not operating. A

The leaves of the engine control .contacts 10 are adjusted so that when spring element 49 is deflected by vane -114 against leaf 40 to close contacts 38 and 42the closed contacts -46 and 48, and contacts 5 2, 56 and 60 are all opened. The leaves of the safety-hold contacts 12 are ,adjusted so that when live leaf 76 is deflected by insulating board 119 to move keeper 73 against feet'72, contacts and 86 are opened, and contacts 80 and 90 are closed.

Conductor connects the ignition leaf 40 -ofthe engine control contacts to the live leaf 76 of the safetyhold contacts. The opposite ends of the solenoid coilV 69 are connected respectively, by Vconductor 14.12 to upper leaf 88, and by conductor 144 to a terminal 146 on kbracket `66. The center of heater coil 102 is connected by conductor 148 or lower leaf 84, while the opposite endsof coil 102 are connected by conductors 150 and 144 to terminal 146. Y

Signal contacts 46 and 48 may be connected to a warning light 151 or buzzer which may be on thecase itself or which maybe at some remote place, such as a maintenance engineers oice,l to signal when the control is in the engine non-operate position. Y K

A light 152 may be mounted on the dial face 27 to position as shown `in FIG.

indicate malfunctioning of the control. The light 152 is connected by. conductor 153 to upper leaf 88, and to ground. Light 152, therefore, is connected in a common circuit with that of coil 69 of electromagnet 68. Consequently when the electromagnet 68 is energized, light 152 will light. Normally the oil or water pressure will build up Within two or three, or at most ten seconds from the time the engine is first started. If the light fails to turn off within that time, it consequently means that coil 69 is still energized and the switch is not in condition for automatic operation. The operator is thus put on guard that something is malfunctioning.

Readily accessible terminals are secured to the backplate 14, as indicated in FIGS. 2 and 3. Insulators 154 prevent the terminals from shorting out with the shell. The control may be readily adapted for operation with either six, twelve, or twenty-four volt operation by connecting resistor coils 156 and 158 between the terminal 146 and the gauges. Battery connection to the control for six, twelve and twenty-four volt operation is through terminal 160. Terminal 162 connects ignition leaf 40 to the appropriate engine control circuits. Similarly terminals`164, 166 and 168 are connected respectively to the first magneto leaf 51, the second magnet-o leaf 54 and ground leaf 58. Terminals 170, 172 and 174 respectively, connect the terminal 14,6 to the gauges for six, twelve and twenty-four battery voltages. Consequently, regardless of the battery voltage of the engine, coil 69 and heater coil `102 will always carry the proper voltage. Terminal 176 connects the signal leaf to the signal circuit.

When the switch is substantially as 'shown as FIGS. 4 and 5, the engine control contacts 10 are in the engine nonoperate condition. The contacts are connected in typical circuits with the controlled engines. The operation of the battery ignition engine is controlled by breaking or making the contacts 38 and 42 in the ignition circuit from the battery. Both the single and dual magneto ignition engines are controlled by making or breaking contacts 52, 56 and 60 to ground the electrical impulses leading to the spark gaps. The diesel engine isvcontrolled by contacts 38 and 42 energizing a solenoid-operated springbias fuel valve operable to stop flow of fuel to the engine.

In operation an operator merely turns the control knob 107 in a counterclockwise directionclockwise as seen in FIGURE 5. The bottom end of vane 114 engages spring element 49 to deflect ignition leaf 40 and reverse the engine control contacts. Continued rotation of the knob permits latching mechanism 14 to maintain the con- `tacts closed by crimp 100 engaging the spring element.

In this reversed contact position, the control is in the engine operate position. Contacts 38 and 42 are closed, and contacts 52, 56 and 60 are open.

Substantially simultaneously with the -bottom end of vane 114 engaging spring element 49, the top end of the vane deilects spring 116 and insulating board 119 against live leaf 76 to move the keeper against feet 72 and to reverse the safety-hold contacts. A circuit is now potentialized through battery leaf 36, contacts 38 and 42, ignition leaf 40, conductor 140, live leaf 76, contacts S and 90, upper leaf S8, coil 69 to terminal 146.

There are two types of indicator gauges used to determine danger operating conditions of an engine, namely the normal closed type similar 1to gauge 18 and the normal open type similar to gauge 19.

In an indicator gauge similar to gauge 18 were used in the safety circuit, the `circuit to terminal 146 as mentioned above Would be completed by conductor 178 through indicator gauge 18. Coil 69 is thus energized to magnetize pole plates 71 and maintain the keeper against feet 72.

The engine control contacts are thus in the engine operative condition and the operator is free to initiate operation of the engine as he pleases.

When the engine is started andthe `oil or water pressure builds up, the needle indicator 128 of gauge 18 separates from stop 130 to break the circuit. Electromagnet coil 69 is thus de-energized. Live leaf 76 then spring returns to the position as shown in FIGURES 4 and 5.

A circuit will now be potentialized from the power source through battery leaf 36, contacts 38 and 42, ignition leaf 40, conductor 140, live leaf 76, contacts 80 and 86, lower leaf 84, conductor 148, heater coil 102 and conductor to terminal 146.

When either of the indicator gauges 18 or 19 indicates a danger operating condition in the engine, the gauge contacts will close and the circuit will be completed. The heater coil 102 will thus be energized to heat bimetal strip 98. The strip will then deflect from engagement with spring element 49 and release the engine control contacts to the position as shown in FIGURES 4 and 5. The operation of the engine will thus be terminated.

If an indicator gauge similar to gauge 19 were used in the safety circuit, the potentialized circuit through the ignition leaf, live leaf and upper leaf to terminal 146 would not be complete. When the operator releases the control knob and the vane is spring returned to the position lshown in FIGURES 4 and 5, live leaf 76 will also return to the position shown in FIGURES 4 and 5. i In this position a circuit the same as described above, including the lower leaf and contacts 80 and 86 to terminal 146 is potentialized. The control is then in automatic safety operation and will respond to a danger operating condition from the indicator gauges as described above.

It may be noted that by manually rotating vane114 in a clockwise direction--counterclockwise as seen in FIG- URE 5--the vane engages bimetal strip 98 and can deect it to release spring element 49 from engagement with crimp 100. Thus the control can be used to manually stop the operation of the engine.

Thus with this invention, an operator can set the control before even starting the engine regardless of the type of indicator gauge used. After the control is once set, it operates automatically not only to permit starting of the engine, but also to safety stop the engine when the engine is in a danger operating condition.

The specific structure-herein shown and described is illustrative only. Various changes in structure will, no doubt, occur to those skilled in the art; and these changes 'are to -be understood as forming a part of this invention insofar vas they fall within the spirit and scope appended claims.

What is claimed is:

l. In a safety relay control having contacts operable to control an internal combustion engine with the'contacts being spring-biased to an engine non-operate position, comprising a latch mechanism having a bimetal strip engageable with the contacts to maintain the contacts in 4an engine operate position, means for automatically unlatching the mechanism including a heater unit associated with the strip operable to distort the strip and position the contacts in the engine non-operate position, and a manually operated setting device operable selectively to set the contacts in either the operate or the non-operate engine control position.

2. In a safety relay control of the type disclosed having contacts operable to control an engine with the contacts being spring-biased to an engine non-operate position, comprising manually operated means to set selectively the contacts in engine operate and non-operate control positions, means to hold the contacts in the engine operate control position, and means operable to detect a danger operating condition of the engine to release the hold means and allow the contacts to spring return to the engine non-operate control position to stop the operation of the engine.

3. In a safety relay control for automatically stopping the operation of a machine by machine control contacts when an indicator gauge indicates a danger operating condition in the machine,.the improvedrelay comprising a of the power source, a heater coil associated with a bimetal latching strip operable to latch the control contacts in a machine operate control position, a hold solenoid, and two pairs of contacts operable to form two circuits with the power source and indicator gauge including, respectively, a hold circuit with the hold solenoid and a safety circuit with the heater coil, where the hold circuit is operable to maintain the control contacts in the operate control condition to provide for initial operation of the machine and Where the safety circuit is operable to energize the heater coil and deflect the bimetal strip to position the control contacts in a machine non-operate position responsive to the danger operating condition.

4. In a safety relay control for automatically stopping the operation of an internal combustion engine by changing the condition of engine control contacts responsive to a danger indication from an indicator gauge, comprising in combination a power source, a heater coil associated with a bimetal latch mechanism operable to maintain the contacts in an engine operate control position, a nold solenoid, a safety-hold relay including the power source and the indicator gauge and two pairs of contacts having connections respectively with the hold solenoid and heater coil, and a manually operated control vane operable to position the engine control contacts in the operate control position, -while simultaneously energizing the safety-hold relay including the hold solenoid to maintain the engine control contacts in the operate position, until the initial operation ofthe engine actuates the indicator gauge to deenergize the safety-hold relay including the hold solenoid and potentializes the safety-hold relay including the l:heater coil, so that when the indicator gauge indicates the danger condition the last-mentioned relay is completed energizing the heater coil to release the latch mechanism and position the engine control contacts in an engine non-operate control position.

5. In an electromagnetic device comprising a support structure, spaced pole pieces supported by the structures, a magnetizable core secured at its ends to the pole pieces, a coil around the core, said pieces extending substantially at right angles from 'the core and having edges converging to a pair of spaced feed defining a plane parallel to the core and at a distance. from the core greater than the radial distance of the coil, a substantially circular keeper having `notched circumferential edges, means supported by the structure and pivotally secured to the keeper to resiliently support the keeper in close proximity of the feet so that the keeper may be moved to abut the feet or to be spaced from the feet, and means to energize the coil to magnetize the pole pieces and hold the keeper against the feet.

6. A safety relay for an internal combustion engine operable to stop the operation of the engine by engine control contacts when a danger operating condition is indicated by an indicator gauge, the combination comprising a power source, an indicator gauge having contacts that are closed when the engine is not running but which open when the engine is running, said contacts automatically closing responsive to a danger operating condition, bimetal latching strip operable to maintain the contacts in an engine operate control position, a heater coil associated with the strip, a hold solenoid, a safety hold relay operable in an engine starting arrangement to complete a circuit through the power source, hold solenoid and indicator gauge to accommodate starting the engine, whereupon the indicator gauge is actuated and the safetyhold relay is automatically actuated to an engine safetylrun arrangement to potentialize a second circuit through the power source, heater coil and indicator gauge, so that when the danger operating condition is indicated by the gauge the second circuit is completed to energize the heater coil and deiiect the bimetal strip to position the engine control contacts in an engine non-operate control position to stop the engine.

.7. 1A safety relay control operable to `stop the operation `s of a machine by machine control contacts when a danger operating condition is signaled by an indicator gauge associated with the machine, with the indicator gauge having closed contacts when the machine is stopped and when the machine is in the danger operating condition, while the contacts are open in the normal operating condition, comprising machine control contacts, a latch mechanism including a bimetal strip operable to maintain the machine control contacts in a machine operate position, a heater coil operable to heat and defect the bimetal strip to position the machine control contacts in a machine non-operate position, a safety-hold relay including an' electromagnet and two pairs of contacts having connections to the indicator gauge with one pair of contacts being normally closed and connected to the heater `coil i tacts open to deenergize the electromagnet and release the pairs of contacts to the original condition to potentialize a second circuit including the heater coil and the indicator gauge, so that when the indicator `gauge contacts close responsive to the danger operating condition the heater coil is energized to heat the bimetal strip` to position the machine control contacts inthe non-operate position and stop the operation of the machine.

8. A safety relay control for automatically stopping the operation of a machine by machine control contacts when a danger operating condition is indicated by an indicatorA gauge having closed contacts when the machine is stopped "f and during the danger operating condition, while the con-Y tacts are open |for the normal operating condition, comprising machine control contacts spring-biased to a machine non-operate position, a latch mechanism including a bimetal strip operable to maintain the machine control conta-cts in a machine operate position, aV heaterV coil operable yto heat and ydeflect the bimetal strip to release the machine control contacts to the machine non-operate position, a safety-hold relay including an electromagnet and,

two pairs of contacts having connections with an indicator gauge, with one pair of contacts being normally closed and being connected to the heater coil While the other pair of contacts is normally open and is connected to the electromagnet, and means to position the machine controlV contacts and reverse the pairs of contacts so that when the machine control contacts are rst positioned in the operate position and the pairs of contacts are reversed, the electromagnet is energized by a circuit including the closed indicator gauge contacts to maintain the pairs of contacts reversed permitting initial operation of the machine, whereupon the indicator contacts separate to deenergize the electromagnet releasing the pairs ,of contacts to the original condition to poten'tialize a second circuit including the heater coil'and the indicator gauge,` so that when the indicator gauge contacts close responsive to a danger operating condition the heater coil is energized and the operation of themachine is automatically stopped.

9. A safety relay control operable to stop the operation of a machine by machine control contacts when an indicator gauge indicates a danger operating condition of the machine, the control being particularly applicable for an indicator gauge having contacts closed in the machine olf and in the danger operating condition While the contacts are open in the normal operating condition, and comprising machine control contacts spring-biased to a machine non-operate position, a latch mechanism including a Vbimetal strip operable to maintain the machinecontrol contacts in a machine Yoperate position, a yheater coil operable to heat and defeat the strip to release the machine control contacts, a power source, a safety-hold relay including an electromagnet and two pairs of contacts, one pair of contacts being normally closed while the other pair yof contacts is normally open,both pairs Yof contacts being connected to an indicator gauge with the normally open contacts includingthe electromagnet and the normally closed contacts including the heater coil, and means to position the machine control contacts in the machine operate position andV to reverse the condition ofthe pairs of contacts, so that when the machine control contacts are first positioned in the machine operate position the electromagnet is energized by a circuit including the normally open contacts, power source and the indicator gaugek to permit initial operation of the machine, whereupon the indicator contacts open to deener'gize the electromagnet releasing the pairs of contacts to the original condition to poten` means including the indicator gauge to actuate auto- Y matically the switching device responsive to a danger tialize a second circuitA including the normally closed Y contacts, power source and the indicator gauge so that when 'a danger oper-ating condition closes the indicator contacts to complete the last mentioned circuit, the control automatically stops the machine,

l0. A safety relaycontrol for automatically` stopping the operation of a machine by machine control contacts responsive to a danger signal from an indicator gauge, comprising a switching device case, machine control con tacts resiliently supported by the case, a biinetal element secured to the case and extending toward and being resiliently urged at ambient temperatures kagainst the machine control contacts, three resilient conductive strips Securedtto the case and extending therefrom in parailel relationship, .a contact on the middle stripy engageable withy contacts on the outside strips, lrespectively, one pair of contacts being normally open while the other pair of contacts is normally closed, a hold solenoid secured to the case, a keeper pivotally supported on the middle strip adjacent the hold solenoid, said middle strip being deflectable so that the keeper may abut the hold solenoid while simultaneously reversing the contacts, a vane rotatably supported 4by the case between themachine control contacts kand the bimetal element and being rotatable to enagge and `deflect the middle strip to abut the keeper with the solenoid and to reverse the contacts, while simultaneously reversing the machine control contacts and permitting the bimetal element to latch the machine control contacts in the reversed position, said solenoid having an electrical connection with the'normally open contact, and a heater coil associated with the bimetal element having an electricalA connection with the normally closed contact, means to rotate the vane andv set the switching device, and' signal to stop the machine4 l1l. A safety relay control for automatically stopping the operation of a machine by machine control contacts responsive to a danger vsignal from an indicator gauge, comprising a case having a pair of spaced brackets, resilient conductive leaves secured at corresponding ends to one bracket and extending therefrom in parallel relationship, machine control contacts on the free ends engageable with the adjacent leaf contact, aV b-imetal element secured to the other bracket extending toward the free ends of the leaves and being resiliently urged at ambient temperature against the leaves, three resilient conductive strips secured at corresponding ends to the case and entering therefrom'in parallel relationship, a contact on the free end of the middle strip engageable with contacts on` noid, said'middle strip being deflectable so that the keeper -may abut the hold solenoid while simultaneously reversing the contacts,1a vane rotatablyv supported intermediate its ends by the case and positioned with one end adjacent the free ends of the leaves between the leaves and rthe bimetal element, spring means on the other end 'of the vane engageable'with the case to maintain the vane in said position, said vane being rotatable to deflect the middle strip to abut the keeper with the solenoidand reverse the contacts, while simultaneously engaging the leaves to reverse the engine control contacts and allowing the bimetal element to latch the leaves in the reversed position, said solenoid having an electrical connection with the normally open contact, a heater coil associated with the bimetal element having an electrical connection with the normally closed. contact, with the solenoid and heater coil havingtelectrical connections to the indicator gauge and being operable to position the machine control contacts, and manually operated means yto rotate the vane.

References Cited in the le of this patent UNITED STATES PATENTS Posnik a Sept. `10,'1957 

11. A SAFETY RELAY CONTROL FOR AUTOMATICALLY STOPPING THE OPERATION OF A MACHINE BY MACHINE CONTROL CONTACTS RESPONSIVE TO A DANGER SIGNAL FROM AN INDICATOR GAUGE, COMPRISING A CASE HAVING A PAIR OF SPACED BRACKETS, RESILIENT CONDUCTIVE LEAVES SECURED AT CORRESPONDING ENDS TO ONE BRACKET AND EXTENDING THEREFROM IN PARALLEL RELATIONSHIP, MACHINE CONTROL CONTACTS ON THE FREE ENDS ENGAGEABLE WITH THE ADJACENT LEAF CONTACT, A BIMETAL ELEMENT SECURED TO THE OTHER BRACKET EXTENDING TOWARD THE FREE ENDS OF THE LEAVES AND BEING RESILIENTLY URGED AT AMBIENT TEMPERATURE AGAINST THE LEAVES, THREE RESILIENT CONDUCTIVE STRIPS SECURED AT CORRESPONDING ENDS TO THE CASE AND ENTERING THEREFROM IN PARALLEL RELATIONSHIP, A CONTACT ON THE FREE END OF THE MIDDLE STRIP ENGAGEABLE WITH CONTACTS ON THE FREE END OF THE OUTSIDE STRIPS, RESPECTIVELY, ONE OF THE CONTACTS BEING NORMALLY OPEN WHILE THE OTHER OF THE CONTACTS IS NORMALLY CLOSED, A HOLD SOLENOID SECURED TO THE CASE ADJACENT THE FREE ENDS OF THE STRIPS, A KEEPER PIVOTALLY SUPPORTED ON THE MIDDLE STRIP ADJACENT THE HOLD SOLENOID, SAID MIDDLE STRIP BEING DEFLECTABLE SO THAT THE KEEPER MAY ABUT THE HOLD SOLENOID WHILE SIMULTANEOUSLY REVERSING THE CONTACTS, A VANE ROTATABLY SUPPORTED INTERMEDIATE ITS ENDS BY THE CASE AND POSITIONED WITH ONE END ADJACENT THE FREE ENDS OF THE LEAVES BETWEEN THE LEAVES AND THE BIMETAL ELEMENT, SPRING MEANS ON THE OTHER END OF THE VANE ENGAGEABLE WITH THE CASE TO MAINTAIN THE VANE IN SAID POSITION, SAID VANE BEING ROTATABLE TO DEFLECT THE MIDDLE STRIP TO ABUT THE KEEPER WITH THE SOLENOID AND REVERSE THE CONTACTS, WHILE SIMULTANEOUSLY ENGAGING THE LEAVES TO REVERSE THE ENGINE CONTROL CONTACTS AND ALLOWING THE BIMETAL ELEMENT TO LATCH THE LEAVES IN THE REVERSED POSITION, SAID SOLENOID HAVING AN ELECTRICAL CONNECTION WITH THE NORMALLY OPEN CONTACT, A HEATER COIL ASSOCIATED WITH THE BIMETAL ELEMENT HAVING AN ELECTRICAL CONNECTION WITH THE NORMALLY CLOSED CONTACT, WITH THE SOLENOID AND HEATER COIL HAVING ELECTRICAL CONNECTIONS TO THE INDICATOR GAUGE AND BEING OPERABLE TO POSITION THE MACHINE CONTROL CONTACTS, AND MANUALLY OPERATED MEANS TO ROTATE THE VANE. 